This invention relates to a method for electroplating of micron particulates with metal or alloy coatings.
Particulates of small size in micrometer order, which include particles, platelets, flakes, whiskers and short or chopped fibers, have been well developed and been widely used as additives, reinforcements and functional elements in plastics, metals or alloys, ceramics and other materials to greatly improve the performance of the products.
Based on the excellent properties of base particulates, since metal coated particulates introduce extra properties of metal coatings and an improved surface, they represent another generation of composite particulates and have important applications in many areas.
Metal coatings on the particulates can be obtained by many techologies, such as chemical vapor deposition (CVD) process, physical vapor deposition (PVD) process and autocatalytic (electroless) plating process. However, the drawbacks of these processes include limited kinds of metal which can be coated on the particulates, relatively low metal deposition rate and high cost.
It is well known that, compared to other coating processes, the electroplating process has the advantage of high coating efficiency, high coating quality, versatility in various metal and alloy coatings, wide range of coating thickness and relatively low cost. However, the small size (&lt;300 .mu.m), irregular morphology and high specific surface area of the small sized (&lt;300 .mu.m) particulates made it impossible to use conventional electroplating processes to obtain metal coatings on these micron particulates.